bool(false)
The full debugging output is shown below:

PHPMailer Object
(
[Version] => 5.2.22
[Priority] =>
[CharSet] => UTF-8
[ContentType] => text/plain
[Encoding] => 7bit
[ErrorInfo] => SMTP Error: Could not authenticate.
[From] => fldrwebmaster@gmail.com
[FromName] => FLDR Webmaster
[Sender] => fldrwebmaster@gmail.com
[ReturnPath] =>
[Subject] => WP Mail SMTP: Test mail to larkart@yahoo.com
[Body] => This is a test email generated by the WP Mail SMTP WordPress plugin.
[AltBody] =>
[Ical] =>
[MIMEBody:protected] => This is a test email generated by the WP Mail SMTP WordPress plugin.

[MIMEHeader:protected] => Date: Sun, 10 Dec 2017 20:22:25 +0000
To: larkart@yahoo.com
From: FLDR Webmaster
Subject: WP Mail SMTP: Test mail to larkart@yahoo.com
Message-ID: <79cdd331afb56f55a768c639edf117f4@fldr.org>
X-Mailer: PHPMailer 5.2.22 (https://github.com/PHPMailer/PHPMailer)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8

[mailHeader:protected] =>
[WordWrap] => 0
[Mailer] => smtp
[Sendmail] => /usr/sbin/sendmail
[UseSendmailOptions] => 1
[PluginDir] =>
[ConfirmReadingTo] =>
[Hostname] =>
[MessageID] =>
[MessageDate] => Sun, 10 Dec 2017 20:22:25 +0000
[Host] => smtp.gmail.com
[Port] => 465
[Helo] =>
[SMTPSecure] => ssl
[SMTPAutoTLS] => 1
[SMTPAuth] => 1
[SMTPOptions] => Array
(
)

[Username] => fldrwebmaster@gmail.com
[Password] => Stw1daat@58
[AuthType] =>
[Realm] =>
[Workstation] =>
[Timeout] => 300
[SMTPDebug] => 0
[Debugoutput] => echo
[SMTPKeepAlive] =>
[SingleTo] =>
[SingleToArray] => Array
(
)

[do_verp] =>
[AllowEmpty] =>
[LE] =>

[DKIM_selector] =>
[DKIM_identity] =>
[DKIM_passphrase] =>
[DKIM_domain] =>
[DKIM_private] =>
[DKIM_private_string] =>
[action_function] =>
[XMailer] =>
[smtp:protected] => SMTP Object
(
[Version] => 5.2.22
[SMTP_PORT] => 25
[CRLF] =>

[do_debug] => 0
[Debugoutput] => echo
[do_verp] =>
[Timeout] => 300
[Timelimit] => 300
[smtp_transaction_id_patterns:protected] => Array
(
[exim] => /[0-9]{3} OK id=(.*)/
[sendmail] => /[0-9]{3} 2.0.0 (.*) Message/
[postfix] => /[0-9]{3} 2.0.0 Ok: queued as (.*)/
)

[smtp_conn:protected] =>
[error:protected] => Array
(
[error] =>
[detail] =>
[smtp_code] =>
[smtp_code_ex] =>
)

[helo_rply:protected] =>
[server_caps:protected] =>
[last_reply:protected] => 221 2.0.0 closing connection y23sm3172981qtj.24 – gsmtp

)

[to:protected] => Array
(
[0] => Array
(
[0] => larkart@yahoo.com
[1] =>
)

)

[cc:protected] => Array
(
)

[bcc:protected] => Array
(
)

[ReplyTo:protected] => Array
(
)

[all_recipients:protected] => Array
(
[larkart@yahoo.com] => 1
)

[RecipientsQueue:protected] => Array
(
)

[ReplyToQueue:protected] => Array
(
)

[attachment:protected] => Array
(
)

[CustomHeader:protected] => Array
(
)

[lastMessageID:protected] => <79cdd331afb56f55a768c639edf117f4@fldr.org>
[message_type:protected] => plain
[boundary:protected] => Array
(
[1] => b1_79cdd331afb56f55a768c639edf117f4
[2] => b2_79cdd331afb56f55a768c639edf117f4
[3] => b3_79cdd331afb56f55a768c639edf117f4
)

[language:protected] => Array
(
[authenticate] => SMTP Error: Could not authenticate.
[connect_host] => SMTP Error: Could not connect to SMTP host.
[data_not_accepted] => SMTP Error: data not accepted.
[empty_message] => Message body empty
[encoding] => Unknown encoding:
[execute] => Could not execute:
[file_access] => Could not access file:
[file_open] => File Error: Could not open file:
[from_failed] => The following From address failed:
[instantiate] => Could not instantiate mail function.
[invalid_address] => Invalid address:
[mailer_not_supported] => mailer is not supported.
[provide_address] => You must provide at least one recipient email address.
[recipients_failed] => SMTP Error: The following recipients failed:
[signing] => Signing Error:
[smtp_connect_failed] => SMTP connect() failed.
[smtp_error] => SMTP server error:
[variable_set] => Cannot set or reset variable:
[extension_missing] => Extension missing:
)

[error_count:protected] => 2
[sign_cert_file:protected] =>
[sign_key_file:protected] =>
[sign_extracerts_file:protected] =>
[sign_key_pass:protected] =>
[exceptions:protected] => 1
[uniqueid:protected] => 79cdd331afb56f55a768c639edf117f4
)